1. Field of the Invention
An aspect of the present invention relates to an image forming apparatus according to an electrophotography process. More particularly, an aspect of the present invention relates to a process cartridge of the image forming apparatus.
2. Description of the Related Art
A conventional image forming apparatus such as a copier, a printer, a facsimile, and a word processor, which uses an electrophotography process, generally employs a process cartridge. If the process cartridge is applied, a user may efficiently repair the apparatus without needing a skilled repairman. As such, the usefulness of the apparatus may be much improved. Accordingly, these image forming apparatuses have come into wide use.
The process cartridge comprises a development cartridge, and a toner cartridge detachably attached to the development cartridge to supply toner. The development cartridge has a toner inlet port and a toner inlet port cover, and the toner cartridge has a toner supply part with a toner supply port. The toner inlet port of the development cartridge should be opened and closed as the toner cartridge is engaged with and disengaged from the development cartridge. To this end, the toner inlet port cover of the process cartridge slidingly opens and closes the toner inlet port in association with the engagement and disengagement of the toner cartridge with respect to the development cartridge.
FIGS. 1A through 1D are views to explain the structure of opening and closing of toner inlet port of a general process cartridge. Reference numeral 1 designates a development cartridge housing, and has a toner inlet port 1a. A toner inlet port cover 2 is movably formed at the development cartridge housing 1 to open and close the toner inlet port 1a. A toner cartridge 3 has a lever 4 elastically biased downward by a toner supply port 3a, a locking protrusion 3b, and a spring 4a. The development cartridge housing 1 also has a guide protrusion 1b. 
As the toner cartridge 3 is slid in the development cartridge during an engagement process, the locking protrusion 3b of the toner cartridge 3 comes into contact with a leading end of the toner inlet port cover 2 (see FIG. 1B) so that the toner inlet port cover 2 moves in the direction toward the right side of the FIGs. and the toner inlet port 1a of the development cartridge is opened.
FIG. 1C is a view of the toner cartridge 3 completely mounted to the development cartridge. As shown, the toner supply port 3a of the toner cartridge 3 is aligned with the toner supply port 1a of the development cartridge so that toner may be supplied therethrough, and the lever 4 of the toner cartridge 3 is inserted in a recess 2a of the toner inlet port cover 2.
Here, as the toner cartridge 3 is pulled out during a disengagement operation, the toner inlet port cover 2 moves in the direction toward the left side of the FIGs. as a result of the lever 4 being withdrawn from the recess 2a so that the toner inlet port 1a may be closed. The lever 4 is lifted by the guide protrusion 1b (see FIG. 1C) of the development cartridge out of the recess 2a of the toner inlet port cover 2 just before completely closing the toner inlet port 1a so that the toner cartridge 3 may be disengaged.
FIG. 1D is an enlarged view of a structure of the toner inlet port cover 2 slidingly engaged with the development cartridge housing 1. As shown, the development cartridge housing 1 has a recess part 11 and the toner inlet port cover 2 has a protrusion part 21 inserted in the recess part 11 so that the toner inlet port cover 2 can move laterally, without separating vertically.
However, sealing the general process cartridge with the above structure is difficult. In other words, as the toner cartridge is engaged with the development cartridge, the toner inlet port 1a of the development cartridge should be aligned with the toner supply port 3a of the toner cartridge 3, and there should be no gap between the toner inlet port 1a and the toner supply port 3a. If there is a gap, toner particles with sizes less than 10 μm leak out as supplied. To prevent this, a sponge seal should be attached between the toner cartridge and the development cartridge. However, the sponge seal interferes with the smooth movement of the toner inlet port cover 2 and operations of the lever 4. Thus, the above structure may not be compatible with the sponge seal and an image density may be deteriorated due to the toner leakage.
Additionally, the conventional process cartridge has a structure that slidingly moves the toner inlet port cover 2 by using the lever 4 elastically biased by the spring 4a. Accordingly, the lever 4 may not be inserted in or not be separated from the recess 2a of the toner inlet port cover 2 so that the toner inlet port cover 2 may not smoothly move and the lever 2 may be occasionally damaged.